include ../_util-fns

:marked
  # Once Upon a Time
  
  # 很久很久以前

  Every story starts somewhere. Our story starts where the [QuickStart](../quickstart.html) ends.
  
  每一个故事，都有一个起点。而我们的故事则开始于[“快速起步”](../quickstart.html)的结尾处。

  Run the <live-example></live-example> for this part.
  
  运行这部分的<live-example></live-example>。

  Create a folder called `angular2-tour-of-heroes` and follow the [QuickStart](../quickstart.html) steps
  which provide the prerequisites, the folder structure, and the core files for our Tour of Heroes.

  创建一个名为`angular2-tour-of-heroes`的文件夹，并且遵循[“快速起步”](../quickstart.html)中的步骤初始化它 —— 
  环境准备、目录结构，并放进我们《英雄指南》的核心文件。
  
include ../_quickstart_repo
:marked
  We should have the following structure:
  
  我们应该有如下目录结构：

.filetree
  .file angular2-tour-of-heroes
  .children
    .file app
    .children
      .file app.component.ts
      .file app.module.ts
      .file main.ts
    .file node_modules ...
    .file typings ...
    .file index.html
    .file package.json
    .file styles.css
    .file systemjs.config.js
    .file tsconfig.json
    .file typings.json
:marked
  ## Keep the app transpiling and running
  
  ## 保持应用不断转译和运行
  
  We want to start the TypeScript compiler, have it watch for changes, and start our server. We'll do this by typing
  
  我们要启动TypeScript编译器，它会监视文件变更，并且启动开发服务器。我们只要敲：

code-example(language="bash").
  npm start

:marked
  This command runs the compiler in watch mode, starts the server, launches the app in a browser,
  and keeps the app running while we continue to build the Tour of Heroes.

  这个命令会在监视模式下运行编译器，启动开发服务器，在浏览器中启动我们的应用，并在我们构建《英雄指南》的时候让应用得以持续运行。
  
.l-main-section
  :marked
    ## Show our Hero
    
    ## 显示我们的英雄
    
    We want to display Hero data in our app
    
    我们要在应用中显示英雄数据

    Let's add two properties to our `AppComponent`, a `title` property for the application name and a `hero` property
    for a hero named "Windstorm".
    
    我们来为`AppComponent`添加两个属性：`title`属性表示应用的名字，而`hero`属性表示一个名叫“Windstorm”的英雄。

  +makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'app-component-1', 'app.component.ts (AppComponent类)')(format=".")

  :marked
    Now we update the template in the `@Component` decoration with data bindings to these new properties.
    
    现在，我们为这些新属性建立数据绑定，以更新`@Component`装饰器中指定的模板

  +makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero')

  :marked
    The browser should refresh and display our title and hero.
    
    保存后，浏览器应该会自动刷新，并显示我们的标题和英雄。

    The double curly braces tell our app to read the `title` and `hero` properties from the component and render them.
    This is the "interpolation" form of one-way data binding.
    
    这里的“双大括号”会告诉应用：从组件中读取`title`和`hero`属性，并且渲染它们。这就是单向数据绑定的“插值表达式”形式。
    
.l-sub-section
  :marked
    Learn more about interpolation in the [Displaying Data chapter](../guide/displaying-data.html).
    
    要了解插值表达式的更多知识，参阅[“显示数据”一章](../guide/displaying-data.html)。
    
:marked
  ### Hero object
  
  ### Hero对象

  At the moment, our hero is just a name.  Our hero needs more properties.
  Let's convert the `hero` from a literal string to a class.

  此时此刻，我们的英雄还只有一个名字。显然，他/她应该有更多属性。
  让我们把`hero`从一个字符串字面量换成一个类。
  
  Create a `Hero` class with `id` and `name` properties.
  For now put this near the top of the `app.component.ts` file, just below the import statement.

  创建一个`Hero`类，它具有`id`和`name`属性。
  现在，把下列代码放在`app.component.ts`的顶部，仅次于import语句。
  
+makeExample('toh-1/ts/app/app.component.ts', 'hero-class-1', 'app.component.ts (Hero类)')(format=".")

:marked
  Now that we have a `Hero` class, let’s refactor our component’s `hero` property to be of type `Hero`.
  Then initialize it with an id of `1` and the name, "Windstorm".
  
  现在，有了一个`Hero`类，我们就要把组件`hero`属性的类型换成`Hero`了。
  然后以`1`为id、以“Windstorm”为名字，初始化它。

+makeExample('toh-1/ts/app/app.component.ts', 'hero-property-1', 'app.component.ts (hero property)')(format=".")

:marked
  Because we changed the hero from a string to an object,
  we update the binding in the template to refer to the hero’s `name` property.

  我们把`hero`从一个字符串换成了对象，所以也得更新模板中的绑定表达式，来引用`hero`的`name`属性。
  
+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero-2')
:marked
  The browser refreshes and continues to display our hero’s name.
  
  浏览器自动刷新，并继续显示这位英雄的名字。

  ### Adding more HTML
  
  ### 添加更多的HTML
  
  Displaying a name is good, but we want to see all of our hero’s properties.
  We’ll add a `<div>` for our hero’s `id` property and another `<div>` for our hero’s `name`.

  能显示名字虽然不错，但我们还想看到这位英雄的所有属性。
  我们将添加一个`<div>`来显示英雄的`id`属性，用另一个`<div>`来显示英雄的`name`属性。
  
+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'show-hero-properties')
:marked
  Uh oh, our template string is getting long. We better take care of that to avoid the risk of making a typo in the template.
  
  啊哦！我们的模板字符串已经太长了。我们最好小心点，免得在模板中出现拼写错误。

  ### Multi-line template strings
  
  ### 多行模板字符串

  We could make a more readable template with string concatenation
  but that gets ugly fast, it is harder to read, and
  it is easy to make a spelling error. Instead,
  let’s take advantage of the template strings feature
  in ES2015 and TypeScript to maintain our sanity.

  我们可以通过字符串加法来制作更可读的模板，但这样仍然太难看了 —— 难于阅读，容易拼错。
  这样不行！我们要借助ES2015和TypeScript提供的模板字符串来保持清爽。

  Change the quotes around the template to back-ticks and
  put the `<h1>`, `<h2>` and `<div>` elements on their own lines.

  把模板的双引号改成反引号，并且让`<h1>`，`<h2>`和`<div>`标签各占一行。
  
+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'multi-line-strings', 'app.component.ts (AppComponent的 模板)')

  .callout.is-important
    header A back-tick is not a single quote
    
    header 反引号不是单引号
    
    :marked
      **Be careful!** A back-tick (`) looks a lot like a single quote (').
      It's actually a completely different character.
      Back-ticks can do more than demarcate a string.
      Here we use them in a limited way to spread the template over multiple lines.
      Everything between the back-ticks at the beginning and end of the template
      is part of a single template string.
      
      **小心！**反引号(`)虽然看起来很像单引号(')，但它们是截然不同的字符。
      反引号能做的可不仅仅是标记字符串的边界。
      在这里，我们只用它来把我们的模板变成多行的，而没有涉及更多用途。
      所有被反引号引起来的部分，都是一个单一模板字符串的一部分。

.l-main-section
:marked
  ## Editing Our Hero
  
  ## 编辑我们的英雄

  We want to be able to edit the hero name in a textbox.
  
  我们想在一个文本框中编辑英雄的名字。

  Refactor the hero name `<label>` with `<label>` and `<input>` elements as shown below:

  把英雄的名字从单纯的`<label>`重构成`<label>`和`<input>`元素的组合，就像下面这样：
  
+makeExample('toh-1/ts-snippets/app.component.snippets.pt1.ts', 'editing-Hero', 'app.component.ts (input元素)')

:marked
  We see in the browser that the hero’s name does appear in the `<input>` textbox.
  But something doesn’t feel right.
  When we change the name, we notice that our change
  is not reflected in the `<h2>`. We won't get the desired behavior
  with a one-way binding to `<input>`.

  在浏览器中，我们看到英雄的名字显示成一个`<input>`文本框。但看起来还是有点儿不太对劲。
  当修改名字时，我们的改动并没有反映到`<h2>`中。使用单向数据绑定，我们没法实现所期望的这种行为。

  ### Two-Way Binding
  
  ### 双向绑定

  We intend to display the name of the hero in the `<input>`, change it,
  and see those changes wherever we bind to the hero’s name.
  In short, we want two-way data binding.

  我们的期望是：在`<input>`中显示英雄的名字，修改它，并且在所有绑定到英雄名字的地方看到这些修改。
  简而言之，我们需要双向数据绑定。

  Before we can use two-way data binding for **form inputs**, we need to import the `FormsModule`
  package in our Angular module. We add it to the `NgModule` decorator's `imports` array. This array contains the list
  of external modules used by our application.
  Now we have included the forms package which includes `ngModel`.
  
  在我们让**表单输入**支持双向数据绑定之前，我们得先导入`FormsModule`模块。
  只要把它添加到`NgModule`装饰器的`imports`数组中就可以了，该数组是应用中用到的外部模块列表。
  这样我们就引入了包括`ngModel`在内的表单依赖包儿。

+makeExample('toh-1/ts/app/app.module.ts', '', 'app.module.ts (FormsModule import)')

.l-sub-section
  :marked
    Learn more about the `FormsModule` and `ngModel` in the
    [Forms](../guide/forms.html#ngModel) and
    [Template Syntax](../guide/template-syntax.html#ngModel) chapters.

    要学习关于`ngModel`的更多知识，参见[表单](../guide/forms.html#ngModel)和
    [模板语法](../guide/template-syntax.html#ngModel)两章

:marked
  Let's update the template to use the  **`ngModel`** built-in directive for two-way binding.

  接下来更新模板，加入用于双向绑定的内建指令**`ngModel`**。

  Replace the `<input>` with the following HTML

  把`<input>`替换为下列HTML
  
code-example(language="html").
  &lt;input [(ngModel)]="hero.name" placeholder="name">

:marked
  The browser refreshes. We see our hero again. We can edit the hero’s name and
  see the changes reflected immediately in the `<h2>`.

  浏览器刷新。又见到我们的英雄了。我们可以编辑英雄的名字，也能看到这个改动立刻体现在`<h2>`中。
  
.l-main-section
:marked
  ## The Road We’ve Travelled
  
  ## 我们已经走过的路
  
  Let’s take stock of what we’ve built.
  
  我们来盘点一下已经构建完成的部分。

  * Our Tour of Heroes uses the double curly braces of interpolation (a kind of one-way data binding)
  to display the application title and properties of a `Hero` object.
  
  * 我们的《英雄指南》使用双大括号(插值表达式 —— 单向数据绑定的一种形式)来显示应用的标题和`Hero`对象的属性。
  
  * We wrote a multi-line template using ES2015’s template strings to make our template readable.
  
  * 我们使用ES2015的模板字符串写了一个多行模板，来让我们的模板更有可读性。
  
  * We can both display and change the hero’s name after adding a two-way data binding to the `<input>` element
  using the built-in `ngModel` directive.
  
  * 为了同时显示和修改英雄的名字，我们还使用了内建的`ngModel`指令，往`<input>`元素上添加了双向数据绑定。
  
  * The `ngModel` directive also propagates changes to every other binding of the `hero.name`.
  
  * 通过`ngModel`指令，这些修改还影响到了每一个对`hero.name`的其它绑定。

  Run the <live-example></live-example> for this part.
  
  运行这部分的<live-example></live-example>。

  Here's the complete `app.component.ts` as it stands now:
  
  完整的`app.component.ts`是这样的：

+makeExample('toh-1/ts/app/app.component.ts', 'pt1', 'app.component.ts')

.l-main-section
:marked
  ## The Road Ahead
  
  ## 前方的路
  
  Our Tour of Heroes only displays one hero and we really want to display a list of heroes.
  We also want to allow the user to select a hero and display their details.
  We’ll learn more about how to retrieve lists, bind them to the
  template, and allow a user to select a hero in the
  [next tutorial chapter](./toh-pt2.html).

  我们的《英雄指南》只显示了一个英雄，而我们真正要显示的是一个英雄列表。
  我们还希望允许用户选择一个英雄，并且显示他/她的详情。
  我们还将学习更多：接收一个列表、把它们绑定到模板，以及让用户选择它。
  这些都在[教程的下一章](./toh-pt2.html)。
